The present invention relates to a stored-program control.
The PCT Publication No. W0 88/10471 describes a programmable controller, which has at least one command storage unit, in which commands for operating programmable controller are stored. The storage unit is linked, via at least one bus system, to a word processor for word processing operations and to a bit processor for bit processing operations. By means of this programmable controller, the results of an analog-signal processing are preprocessed thereby permitting them to be received by the bit processor for the bit processing operation. For this purpose, a decoder is provided, which has inputs connected to the storage unit and to a flag register of the word processor and outputs connected to the bit processor. In each case, the decoder produces a status bit in the form of a binary identifying signal from its input signals, formed from the usual flag signals together with the commands producing the flag signals. The binary identifying signal is sampled by the bit processor through a command assigned to it and stored in the command storage unit at the output of the decoder. By means of this control provided with circuit-engineering measures, combining a word-processing result with the result of the preceding binary processing is possible.
Chapter 2 of the publication Automatisieren mit SIMATIC S5-115U [Automating with SIMATIC S5-115U] by Hans Berger, 1991, ("the Berger article") describes that a result of a binary logic operation (BLO) is stored in the bit processor and is available for further processing. If a statement list consists of several consecutive binary logic instructions, then these are processed in sequence by the bit processor. The result of a logic operation is initially stored in the bit processor and linked with the sampling result of the next instruction, etc. The logic result stored in the flag register of the bit processor prior to the processing of the next instruction is erased after this instruction is processed and replaced by the new logic result.
Chapter 3 of the Berger article describes, on page 108, the processing of a so-called comparison operation. In the comparison operation, two digital values are compared to one another. The result of this processing influences the binary logic result, which means that the previous content of the flag register of the bit processor is altered and is no longer available for a further processing. This previous content of the flag register can be "saved", if it had been previously stored in a special storage area (marker) on the central processing unit. It is possible, using an appropriate program, to read out this storage area and to make the content available for a further processing. However, these measures adversely affect the processing speed during operation of the stored-program control.
The object of the present invention is to create a stored programmable controller which will simplify linking the results of one word processing operation with the results of the preceding binary processing operation.